Path Definition and 1000 Threads

Refer to "2.jpg", it said that the shortest path on the surface of a sphere is Ay-Bx=z , which is a plane passing through the center of the sphere. I cannot really understand about this. Does it mean that the shortest path is a ring that connects two points with its center at the center of the...

I have an argument with classmates about the trajectory that the block will have (circle, ellipse, something else...). The configuration is similar to this image. http://minireference.com/_media/physics/momentum-bullet-speed-block.jpg?w=400 Initially, the block will move horizontally...

What is the difference between path independence and a conservative vector field? It seems like both definitions given in the textbook mean the same. What is the difference between the two? According to wikipedia, path independence is a consequence of a conservative vector field, but...

Please help me to find a formula to determine the actual position of two objects, depending on time. Imagine two identical (mass, size, etc) object, no other effect on them only the gravity of each other (Newton). Let's imagine these objects are non corporal, so they will not collide. The...

Hi And Need Help The main Question is what happens to light and cause go into next medium as total internal reflection happens for incident angles higher than critical angle ? so the main question is why the light path throughout the second medium? We know when light travels from a medium...

Hello, I am having a little difficulty articulating my question, so please bear with me. I understand that when waves occupy the same space at the same time, they interfere. What I am having difficulty visualizing is when two different waves travel different paths and intersect at some point...

Homework Statement Homework Equations The Attempt at a Solution B=\frac{\mu_{0}I}{4\pi}\int \frac{dl\times \hat{r}}{r^{2}}=\frac{\mu_{0}I}{4\pi r^{2}}\int dl\times \hat{r} So I think since when you cross dl with r, you end up with just dl. \frac{\mu_{0} I}{4\pi r^{2}}\int dl l=rθ so dl=rdθ...

I read the Quantum Physics section of the online version of Feynman lectures http://feynmanlectures.caltech.edu/I_02.html#Ch2-S3 and I don't understand the problem with the electrons "breaking away from the nucleus". So why can't the electrons just keep going in and out of the nucleus ?

Homework Statement Use the principle of deformation of path to deduce \int_0^\infty t^n \textbf{cos}(bt) e^{-at}dt=\frac{n!}{e^{n+1}}\textbf{cos}((n+1)\phi) and \int_0^\infty t^n \textbf{sin}(bt) e^{-at}dt=\frac{n!}{e^{n+1}}\textbf{sin}((n+1)\phi) where a>0, b>0, c=\sqrt{a^2+b^2}, and...

SOme one help me with the OPD. How is here the OPD=n2(AB + BC) -n1(AD)? I am not confused with the introduction of 'n'..Rather the path length is confusing me..Why is there a negative sign?

Just need someone to tell me if I'm doing this right. If I have accelerated a particle in which the mean free path is 50nm and I need the collision to be 5eV would this be correct in determining the required electric field strength? 5/.00000005 = 100MV/m

Homework Statement A beam of parallel light rays from a laser is incident on a solid transparent sphere of index of refraction n1 (see figure). (a) If a point image is produced at the back of the sphere, what is the index of refraction of the sphere? (b)What index of refraction, if any, will...

This paper seems to me especially interesting: http://arxiv.org/abs/1308.2946 Purely geometric path integral for spin foams Atousa Shirazi, Jonathan Engle (Submitted on 13 Aug 2013) Spin-foams are a proposal for defining the dynamics of loop quantum gravity via path integral. In order for...

Homework Statement Compute the line integral of \vec{v} = (rcos^{2}\theta)\widehat{r} - (rcos\theta sin\theta)\widehat{\theta} + 3r\widehat{\phi} over the line from (0,1,0) to (0,1,2) (in Cartesian coordinates) The Attempt at a Solution Well, I expressed the path as a...

Why does light follows a path of minimum time? I.e., is there any theory or explanation behind the fermats principle?

as the Electric field is perpendicular to magnetic field , would the over all sum of the sinusoidal waves would turn up to be a helical shape ?

The path described by a constantly accelerating particle is given by: x=c\sqrt{c^2/a'^2+t^2} where a prime denotes an observer traveling with the particle and a letter without a prime a resting observer. If we leave the c^2/a'^2 out it reduces to x=ct, which makes sense. The distance...

Ok so i have a question , for the sake of the argument imagine a infinitely long conducting wire with a given positive potential. Now along that wire in an enclosed non conducting tube around it there is a ionized hydrogen (no electrons for the argument) Now when a conductor like our...

Homework Statement Find the shortest distance between two points using polar coordinates, ie, using them as a line element: ds^2 = dr^2 + r^2 dθ^2Homework Equations For an integral I = ∫f Euler-Lagrange Eq must hold df/dθ - d/dr(df/dθ') = 0 The Attempt at a Solution f = ds = √(1 + (r *...

I am currently in 8th grade. Particle physics fascinates me, and I would like to know ways to get on this career path. Working at LHC/CERN is all I think about. Recommended books, high school programs, extra curricular activities, colleges, internships, and websites would be very helpful for...

Hi, I think some background is necessary: I'm a Psychology undergraduate student. I also really love math. I've incorporated some pure math into my studies - next semester I'll have room for a course on "Foundational Mathematics" (I'm not sure if that's exactly what they call it outside my...

Hey folks, I am currently studying at Ryerson (Toronto, Canada) in Computer Engineering (BEng) and I am starting my 3rd year in September. Since high school, I have been very interested in astronomy and quantam physics (at least what was taugh) and I always postulated my own theories on how...

I found this mechanism(see image) in a very old book in the library.I was wondering if there is any mathematical technique(obviously geometrical) to find out the locus of travel that the links would take(case 1). Also, be able to calculate the displacements(case 2). The problem with the given...

http://www.slideshare.net/viv3ksharma/automatic-school-bell In this circuit I Think the emitter and collector terminal of the transistors T1 & T2 will be reverse. Otherwise the 555 timer will not discharge. Can anyone help pls?

In an automatic school bell circuit, The outputs from 3 to 11 are connected to the base of an NPN (BC547) transistor through 1K resistance. A diode is connected in forward bias in each of those outputs so that only one output sends high pulse to the base of the transistor. When the high pulse is...

Homework Statement A disc is thrown at a 28° angle to the ground. It landed 39.8m away. a) What is the velocity of the disc? b) How long was the disc in the air? Homework Equations ##θ = 28°## ##\vec{Δd}_H = 39.8 m [F]## The Attempt at a Solution a) I was thinking I should use the...

If a gamma ray is being fired and is in turn colliding with electrons and ionizing the electrons in the gamma ray path, where do the electrons tend to? In what direction is the current most likely to flow for a high powered gamma ray ionization?

I would love some clarification on a gamma ray process. This is what I understand so far: Electrons are accelerated at 19MeV at a cathode which is releasing gamma ray photons with an energy of 1.9MeV. Is it possible to generalize the emission number of photons (roughly) to be equal to the...

Hi Guys, I am trying to choose a path in mechanical engineering. I am wondering what braches you guys have had experience with. I thinking like consumer electronics (apple, mircosoft), general mechanical (ford, etc), aero/astro (boeing, Nasa), oil stuff(shell, exxon). Do you guys have any...

Hi, I am trying to prove that any compact metric space that is also locally connected,must be locally path connected. can someone help? thank's in advance.

I've read a solution of a problem, in which there are two different gases in a container, initally at equilibrium and separated by an adiabatic fix wall. At some time, this wall is changed by a diathermic mobile wall, so the equilibrium point changes. You have to find the final state of the...

A ring on curved path (say on bent rod) will move longer distance than the one moves on straight line in same interval of time (the two rings are released simultaneously - one moves on curved path and other one moves horizontally) - How to explain? by which principle one can explain?

Homework Statement The x and y coordinates of a particle moving in the x-y plane are x=8sin(t) and y=6cos(t). What is the equation of the path of the particle? Homework Equations m=\frac{y_2-y_1}{x_2-x_1} y-y_1=m(x-x_1) The Attempt at a Solution I am stuck on how to approach this...

Hello, Does anyone know why we use the root mean square of the relative velocity in calculating the mean free path? As is done in this example: http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/MolecularCollisions.htm Seems like it would make more sense to find the mean of the...

So, if an object is moving in a circular path, it has a force constantly directed to the center acting on it, and this force is perpendicular to the velocity. However, imagine now that it's not moving. How can one get this object to move in a circular pathway using centripetal force? Does the...

So, I'm to show that in spherical coordinates, the length of a given path on a sphere of radius R is given by: L= R\int_{\theta_1}^{\theta_2} \sqrt{1+\sin^2(\theta) \phi'^2(\theta)}d\theta, where it is assumed \phi(\theta), and start coordinates are (\theta_1,\phi_1) and (\theta_2, \phi_2)...

So this is a fairly simple conceptual question: can you estimate/compare the mean free paths for individual components of a mixture of gases? I'm primarily looking at the equation given here and the information accompanying it. Consider the case where we have several individual, separate...

Homework Statement A cylinder rolls without slipping down a hill. It is released from height h. What is its speed when it come down? The cylinder mass may be completely concentrated on the radius R, which is the radius of the cylinder. http://i.imgur.com/Ge3x1nu.png The Attempt at a...

Helloo! I am asked to find the weights of the shortest path from s in a directed Graph G=(V,E), where V={s,a,b,c,d}, E={(s,a),(s,d),(a,b),(a,c),(a,d),(b,s),(b,c),(c,b),(d,a)} and their weights 5,3,6,4,1,3,7,2,2... I used Dijkstra's Algorithm, and I found d[s]=0,d[a]=5,d[b]=11,d[c]=9,d[d]=3...

I'm going through a whole undergrad quantum book (Townsend) by myself. It has a chapter on path integral QM. He said in the intro that it can be skipped, but I was wondering if knowledge of this subject is immediately helpful when starting graduate level quantum. I start grad school in the...

We know that the orbit of a planet and its star is a conic section. For a closed orbit, it will be an ellipse described by x^2/a+y^2/b =1, or its equivalent equation in r and θ What would be the equation of the path under GR? and how will it approximate to a conic section when r(s)/r tends to...

1. The problem: A 5-kg block is moved from the ground to a height of 1 m via two different routes, vertically and along an inclined plane with angle of 30° to the horizontal. How much work is done on the block against gravity in each case? Homework Equations W=Fcosθd where θ is between...

Homework Statement model the run up a bowler takes before he throws the cricket ball Homework Equations model the path of the cricket ball The Attempt at a Solution we can make any assumption. if anyone good in physics please helo me model it.

I've been mulling this over all weekend, and I've decided to get some help on this. The problem is writing a function to describe a bullet's path. I've asked two people about it my Physics teacher (who said he didn't know how) and my French teacher, who was a nuclear engineer for the US Navy...

Homework Statement A pilot must travel directly to a town 500 miles away in a directions 20 degrees east of south from her present position. There is a steady 40 mph wind blowing west to east. Her plane's cruising speed through calm air is 95 mph. Using vector, what must be the plane's...

Path Integrals-- Multivariable Calculus Hi all-- really stuck here, help would be greatly appreciated. :) 1. Evaluate ∫F
ds (over c), where F(x, y, z) = (y, 2x, y) and the path c is defined by the equation c(t) = (t, t^2, t^3); on [0, 1]: 2. Homework Equations L = sqrt(f'(t)^2 +...

Homework Statement a) Prove that m (d^2s/dt^2) = Ftang, the tangential component of the net force on the bead. [hint] one way to do this is to take the time derivative of the equation v^2=v(dot)v. The left side should lead you to (d^2s/dt^2), and the right side should lead to Ftang. b)...

Hi, I am reading through the book "Quantum Mechanics and Path Integrals" by Feynman and Hibbs and am having a bit of trouble with problem 3-12. The question is (all Planck constants are the reduced Planck constant and all integrals are from -infinity to infinity): The wavefunction for a...

I've read so much stuff on the internet including other threads on the forum but am still confused. When a car is making a turn on a level road, WHY does the static friction point inward? From what I've learned the direction of static friction points in the direction opposing movement but the...

I am currently a year 2 uni student in University of Sydney. I want to continue my career as a physicist and work in University while doing my research. I am wondering 1) How good does your academic record need to be in order to do Phd? 2) Does it cost less or more comparing to bachelor...